diff --git a/event.py b/event.py
index 50de9cc..eb96711 100644
--- a/event.py
+++ b/event.py
@@ -21,7 +21,7 @@ class Event():
         sql = f"""SELECT mem_usr_id, mem_leader, mem_count_guests
                   FROM {self.admidio.prefix}_members
                   WHERE mem_rol_id = {self.rol_id}
-                  AND mem_end = 9999-12-31"""
+                  AND mem_end = '9999-12-31'"""
         self.__c.execute(sql)
 
         for row in self.__c.fetchall():
diff --git a/group.py b/group.py
index bbe4412..b623eb6 100644
--- a/group.py
+++ b/group.py
@@ -12,7 +12,7 @@ class Group:
         sql = f"""SELECT mem_usr_id, mem_leader
                 FROM {self.admidio.prefix}_members
                 WHERE mem_rol_id = {self.id}
-                AND mem_end = 9999-12-31"""
+                AND mem_end = '9999-12-31'"""
         self.__c.execute(sql)
 
         for row in self.__c.fetchall():